1. Field of the Invention
This invention relates to a press for forming sheet metal elements, comprising a frame, which is connected to a coordinate deck on one side thereof, upper and lower turntables carried by said frame, a plurality of angularly spaced apart upper press tools, which are carried by the upper turntable at its periphery and vertically adjustable relative to the upper turntable, a plurality of lower press tools, which are carried by the lower turntable and axially aligned with respective ones of the upper press tools, and a ram, which is carried by the frame and adapted to be coupled to each of said upper press tools in dependence on the angular position of the upper turntable.
2. Description of the Prior Art
Such presses afford the advantage that different press tools can be used to act on each workpiece without a need for an alteration of the press with high expenditures of time and labor. The press tools to be used at a time can be moved to an operating position by a rotation of the turntables carrying said press tools. In said operating position, the selected upper press tool is coupled to the ram for the working stroke. For that purpose the workpiece is so positioned on the coordinate deck associated with the press that the press tools act on the desired portion of the workpiece. The workpiece is gripped by grippers and by means of said grippers is displaced on the coordinate deck and those parts of the deck which are adjacent to the range of movement of the grippers must be lowered. In spite of that measure, the grippers cannot be moved as closely as desired to the upper and lower press tools which are in operating position because the adjacent lower press tools will obstruct the motion of the grippers adjacent to the press tools which are in operating position. For this reason the dimensions of the workpieces, particularly of relatively small workpieces, must be larger than the specified final dimensions so that the quantity of waste and the working time are increased and additional operations are required.
The need for larger dimensions may be avoided if the grippers grip the workpiece at different portions. But that regripping will necessarily involve considerable inaccuracies and an additional increase of the working time.